Lithographic printing machine



May 7, 1935. A. J. HORTON LITHOGRAPHIC PRINTING MACHINE I Filed March16, 1932 INVENTOR Patented May 7, 1935 UNITED STATES PATENT- OFFICELITHOGRAPHIC PRINTING MACHINE Application March 16, 1932, Serial No.599,135

dclaims.

This invention relates in general to improvements in lithographicmechanism, having for an object the provision of an improved method andmeans for dampening printing plates.

Another object is to provide an improvement in dampening mechanism forlithographic printing machines which will convey an equally distributedamount of 'moisture from the water fountain to the dampening rollers,and consequently, to the printing plates.

A further object is to provide in a rotary lithographicpress,distributing and fountain rollers of a special material particularlydesigned and constructed for longer life, greater strength and rigidity,and particularly adapted to be moistened easily and retain moistureuniformly while preventing the tendency prevalent in conventionalrollers towards the formation of drops of liquid and dry patches orplaces on the distributing and carrying rollers resulting in a conditionunfavorable to satisfactory lithographic printing.

A still further object is the provision of novel distributing andfountain rollers of a special noncorrodible material particularlyadapted to be ground, sand-blasted, or otherwise given a desired finishor grain best suited to be uniformly moistened and for uniformlytransferring moisture from their surfaces to coactlng rollers, whilehighly resistant to taking on in use, a gloss or polished surfacecharacteristic of softer metals.

It is also an object of the invention to provide a lithographic rollerof generally improved construction, whereby the device will be simple,durable and inexpensive in construction, as well as convenient,practical, serviceable and efficient in its use.

In the lithographing art, it has been customary to employ moisturedistributing rollers made of brass and printing plates formed ofaluminum or zinc. The water or desensitizing solutions customarilyemployed for the purpose of moistening or dampening the said printingplates, frequently has a corrosive or oxidizing effect on thedistributing and fountain rollers which are moistened with or immersedin the said solution. The corrosive action or a change in the surfacedue to operation, it would appear, results in the formation of a surfacecondition prejudicial to satisfactory lithographic printing. Under thesecircumstances it has been found that the surface of the distributingroller and of the fountain roller may be dry in spots, with a tendencytowards the formation of drops of liquid thereon, rather than have afilm of moisture uniformly distributed thereover.

Although under some conditions the action of electrolysis will hastenthe corrosion of the rollers heretofore used, particularly when strongacidulous or alkaline dampening solutions are employed, there is also atendency for the rollers in general use to acquire a surface on whichthe moisture is not evenly distributed, the moisture forming in patcheswith dry areas between them on which ink adheres. This results in anuneven distribution of moisture on the surface of the printing plateand-in order to insure that sufficient moisture is provided for allparts of the printing plate it is necessary to feed a greater amount ofmoisture than is required. This results in feeding excess moisture tosome portions of the plate, and as is well known, excess moisture actsto dilute the ink, and solid colors in the printing will show streaks oflighter color. With the roller disclosed herein, an even film ofmoisture is maintained on its surface and it has been found that thequantity of water delivered by the fountain roller to the ductor can begreatly decreased, thus avoiding feeding of excess moisture to someparts of the plate in order to insure that suflicient is fed to allparts.

The phenomenon of surface tension also has been found to play animportant part in the tendency of liquids to diffuse themselves over asurface, it being observed that the slightest impurity or dissolvedsubstance changes the surfacetension of the liquid. Brass, as is wellknown, is particularly susceptible to slight corrosion under ordinary oratmospheric conditions and it has been found that a comparatively slightand sometimes almost imperceptible corrosion will play an undue part inthe way of a non-uniform distribution ofthe dampening liquid over thesaid distributing and fountain rollers; when this metal is used.

Aluminum rollers have also been used, but it has been found that theacids commonly used in the moistening fluid have a deleterious effect onthem and in time their surface becomes roughened, resulting in imperfectmoisture distribution to the plate.

From actual experience over an extended period, it has been found thatthe difficulties due to corrosion of the distributing or fountainrollers either by the liquids employed or by oxidation due to ordinaryatmospheric conditions can be avoided without the necessity of makingthem of the same metal as the printing plates ashas been suggested forthe purpose of avoiding electrolyticaction, the desired avoidance ofcorrosion being eifected by the means employed in the present invention,in a manner that will lend itself to practically any type oflithographic mechanism employing printing plates, which latter may be ofany desired metal or alloy conventional in the art.

Briefly, the present method and means broadly contemplates the use ofdistributing and fountain rollers formed of a practically non-corrodiblemetal preferably ferrous, with which printing plates of any conventionalor desired composition of metal may be used. In carrying the inventioninto practice rustless iron or so-called stainless steel is employed asa material admirably adapted to yield the desirable results pointed outabove. So far as applicant is aware rustless iron or stainless steel hasnever hitherto been employed for use with printing machines or moreparticularly, as a material for moisture distributing and water fountainrollers.

Regardless of the material of the printing plates, the moisturedistributing and water fountain rollers, if made of the rustless iron orsteel indicated, will remain uncorrodedin the presence of the water ordampening fiuid employed, and in addition will retain their surface asoriginally finished over a far longer period of time than is possiblewith softer metals.

In accordance, therefore, with the present invention, a distributingroller of rustless iron or ferro-chorimum alloy is provided, andpreferably a water fountain roller made of the same material. If desiredthe body portion alone may be composed of rustless iron while the shaftand journals may be composed of ordinary iron or steel. The surface ofthe said ferrous alloy roller, or the body portion thereof, is preparedto a mat finish or finished in a manner most favorable to beingmoistened and not to a glass finish or polish or a point of finenesswhere the water or dampening fluid has a tendency to form globules.

The surface of the above-mentioned rustless ferrous alloy roller, afterbeing finished, when viewed through a microscope, presents theappearance of a surface having minute pits or indentations distributedwith great uniformity and regularity of spacing. These microscopic andevenly distributed pits orindentations serve to facilitate the uniformdiffusion of liquid applied thereto and to prevent the formation ofdrops orglobules of liquid which a surface too rough or too polished isprone to occasion. Furthermore, the surface of this ferrous alloyroller, although in daily use, will be found to be in large measure freeof the impurities, by reason of its non-corrodible and rust-proofcharacter, so frequently occurring with the conventional rollers incommon use.

The preferred embodiment of the invention is illustrated in theaccompanying drawing, wherem:

Figure 1 is a plan view of a distributing or car rying roller embodyingmy invention;

Figure 2 is a diagrammatic view, partly in section, of such parts of alithographic printing machine, as will sumce to an understanding of theinvention.

With more particular reference to the drawing wherein similar charactersof reference indicate corresponding parts in the views, the numeral 8designates a frame member forming a part of a lithographic printingmachine on which is secured or formed integrally'therewith, a tray orfountain l0 adapted to" contain water or the usual dampening'soluti'oncomposed of acidulated water. Rotatably mounted in the tray [0 onbearing brackets ll secured to the frame member 8, is a fountain orcarrying roller 12 which, in accordance with the present invention, isformed of rustless iron or stainless steel, preferably ground,sand-blasted, or otherwise finished with a grained or mat surface, bestadapted to uniformly take-up and convey liquid from the tray l0, thesaid fountain roller l2 being ccactingly and intermittently engaged by aductor roller I3 revolvably mounted on arms I! secured to a rockingshaft IS. A material or alloy employed for the body portion of thefountain roller II, which has been found to yield the desirable resultsindicated above has the following percentage composition:

Percent Carbon less than .10 Manganese less than .40 Silicon less than.50 Sulphur less than .03 Phosphorous less than .03 Chromium 16.00 to18.00 Iron 80.00 to 83.00

The ductor roller I 3, which is moistened by the fountain roller I2, isalso adapted to intermittently or periodically engage a revolvablymounted distributing roller I6 the body portion of which is formed, asan important feature of the invention, of the ferrous alloy indicatedabove, the said distributing roller being in engagement with a pair ofdampening rollers 11, which bear constantly against a printing surfaceof, or a plate I8 secured on, the plate cylinder I8.

It will be understood that when the machine is in operation, the ductorroller l3, which is generally covered by a fabric, will oscillate backand forth between the fountain roller l2 and the distributing roller l6,thus carrying or transferring water or desensitizing liquid from thetray III to the distributing roller IS, the grained surface of thelatter being dampened thereby, but almost immediately dried by contactwith the absorbent coveringof the dampening rollers I! with which it isin constant engagement, the latter rollers H being also engaged with theprinting cylinder I! or a printing plate ii thereon.

The physical characteristics of the rollers l2 and It, by reason oftheir uniformly finished surfaces and their proof against corrosion, aresuch as to insure a comparative freedom from surface imperfectionsarising from oxidation and other corrosion, and also to assure a veryuniform distribution of liquid applied to their surface.

Hitherto the use of iron or steel as a material for lithographic rollerswas impractical owing to the proneness of such material to corrosion bythe water or desensitizing solutions employed. As now, indicated,however, rustless iron or stainless steel not only permits the use of aroller having all the natural advantages inherent in ordinary iron andsteel, so far as maximum strength, rigidity and long life are concerned,but by reason of its chromium content and other constituents it isparticularly adapted to be ground to and retain the desired or matfinish. and above all, has the superlative non-corrodible characteristicmentioned above which renders it superior to any other material yetemployed for distributing and fountain rollers.

The composition of the alloy described above may be varied somewhatwithout materially altering its properties so far as resistance tocorrosion by the solutions and reagents ordinarily employed areconcerned.

For example, the chromium content may be reduced to 12 or 14 percent orincreased to 25 or 30 percent, with the rest of the ingredients in thesame proportion and the iron content increased or decreased in an amountcorresponding to the decrease or increase in chromium. Nickel may beemployed in the alloy also in amounts varying from a trace to 10%without substantially altering the corrosion-resisting properties of thealloy to ordinary reagents or solutions employed in lithographicprinting.

None of the solutions employed for the purpose of moistening thedampening rollers of a lithographic machine or encountered in daily lifehave the slightest corrosive effect on the ferrous alloy rollersemployed in mechanism constructed in accordance with the presentinvention.

It will be understood that the invention may be embodied in otherspecific forms without departing from the spirit or essential attributesthereof, and it is therefore desired the present embodiment beconsidered in all respects as illustrative and not restrictive,reference being bad to the appended claims rather than to the foregoingdescription to indicate the scope of the invention.

What I claim is:

1. In a dampening mechanism for a lithographic printing machine, adistributing roller and a fountain roller, both of said rollers beingformed of rustless ferrous alloy and having their exterior surfacesgrained to a mat finsh.

2. In a dampening mechanism for a lithographic printing machine, adistributing roller formed of a non-corrodible ferrous alloy havingapproximately the following composition:

Percent Carbon less than .10 Manganese less than .40 Silicon less than.50 Sulphur less than .03 Phosphorous less than .03 Chromium 16.00 to18.00 Iron 80.00 to 83.00

3. A dampening roller for a lithographic printing machine formed of aferrous alloy commonly known as rustless iron or stainless steel havinga molecular structure which adapts it to receive a durable grainedfinish, and having an afiinity for the moistening solutions commonlyemployed in lithographic printing; whereby when its surface is somoistened. it is repellent to ink.

4. A dampening roller for a lithographic printing machine formed of aferrous alloy commonly known as rustless iron or stainless steel havinga characteristic twin or parallel grain molecular structure which adaptsit to receive a durable mat finish, and having an aflinity for themoistening solutions commonly employed in lithographic printing; wherebywhen its surface is so moistened it is repellent to ink.

. ALBERT J. HORTON.

